Method of manufacturing filament supporting assemblies for lamps



Dec. 13, 1938.

vL.S.GREENMUN METHOD 0F MANUFACTURING FILAMENT SUPPORTING ASSEMBLIES FOR LAMPS Original Filed Aug. 8, 1935 INVENTOR. 'Green man BY feo 11?.

ATTORNE 6.

Patented Dec. 13, 1938 UNITED STATES- PATENT OFFICE DIETHOD OF MANUFACTURING FILAIVIENT SUPPORTING ASSEMBLIES FOB. LAMPS Leo S. Greenmun, Binghamton, N. Y., assigner to Dayatnite Lamp Corporation, Newark, N. J., a. corporation of Delaware Application August 8, 1935, Serial No. 35,330

Renewed January 19, 1938 s claims. v. (o1. is-7s) place about the upper end of said slender tube a short glass tube having a flared base and to insert in properly spaced arrangement in the space between these tubes the desired number of filament supporting of lead-in wires, the asl5 sembled parts being then heated at their upper ends and pressed together so as to fuse the inner and outer tubes to each other and seal the lead-in wires in place.

While the fused .upper end of the assembly is still sufficiently hot, air under pressure is admitted into the lower end of the slender inner tube and in this way a passage way leading from the interior of the upper end of the inner tube to the exterior surface of the outer tube is formed, which provides means through which in subsequent operations the lamp is evacuated and charged with an inert gas such as nitrogen.

The filament is then' mounted on the lead-in wires and the bulb positioned overl the filament supporting assembly. The flared base of the outer tube is then fused to the base of the bulb and the bulb is then evacuated. During these operations the lower end of the inner tube is supported in a suitable fixture for rotation about its axis. Due to the length of the inner tube and the fused condition of the various elements during the assembling operations, the filaments are often so mounted as to be ecc'entrically disposed with relation to the bulb and other parts of the 40' lamp.

This condition is partially corrected by the' operators who while the assembly is thus supported, and while the fused area is still hot, r sights or adjusts the filament by eye. This 4 procedure is necessarily characterized by a lack of uniformity with the result that the lamps are defective and will not function in a head lamp without creating a distorted screen image.

The dimculties which lie in the way of securing accuracy and uniformity reside in the fact that the inner tube is not concentric with the balance oi the assembly, and is vof such small diameter I and so long that when the assembly is mounted in the sealing and evacuating machines, the upper end of the assembly is not in alignment with the lower end of the inner tube.

The present invention has as its principal object the provision of a filament supporting assembly and method of manufacturing the same, the use of which will not only avoid the aforesaid difficulties and inaccuracies but which will result in the manufacture of lamps of high qualityin ycommercial quantities and at low cost.

To the accomplishment of the foregoing and l0 related ends, the invention, then, comprises the features hereinafter fully described, and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments 15 of the invention, these -being indicative however,

of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing:

Fig. l is a cross-sectional view showing the 20 first step in the manufacture of the filament supporting assembly; Fig. 2 is a View showing the second step in such manufacture; Fig. 3 is a similar .View showing a filament supporting assembly in the final stages of its manufacture; 25 Figs. 4, 5, and 6, are transverse cross-sectional views taken on the lines 4 4, 5 5, and 6-6 respectively of Fig. 3; Fig. '7 is a cross-sectional view showing the method of securing the bulb of a lamp to the filament supporting assembly 30 and Fig. 8 is a transverse cross-sectional view takenon the line 8--8 of Fig. 7.

Referring to said drawing, l'. provide a glass tube I which is' of a diameter substantially the same as that of the outer tube used in existing 35 filament supporting assemblies and of a length considerably in excess of the length of the tube used in such existing assemblies.

This tube is supported vertically for rotation about its axis in a recess 2 of a fixture 3, the 40 walls of the recess closely engaging the outer wall of the tube at the lower end of the latter. Secured to the fixture 3 is a plunger 4 which extends upwardly for a considerable distance into the tube l and closely engages the inside wall of the latter. While the tube is rotating, heat is applied to the portion of the tube designated A, that is, a portion of the tube just below the upper end of the plunger 4. 'When thel portion A of the tube has been sufficiently heated, the fixture 3 and plunger 4 are moved upwardly by a series of short movements. During this upward movement of the fixture and plunger, the upper end of the tube is restrained from moving vertically, and consequently, pressure is applied to the lower end of the tube, resulting'in the formation of a flange 5 at the heated portion A of the tube. This flange takes the place of the flared bottom of the outer tube in the existing types of lament provides an accurate tube to start with and a tube of fairly large diameter, which can, in subsequent operations, be held in such a manner as to avoid imparting an eccentric movement to the upper end of the tube, thereby insuring accurate placement of the filament.

The tube is then removed from fixture 3 and placed in a fixture 6, which is not provided with a plunger. With the tube thus supported, filament supporting or lead-in wires 1, 8, and 9 are inserted in properly spaced relation within the tube and heat is applied to the areas of the tube designated by reference characters B and C, as shown in Fig. 3. When the tube has become sufficiently heated at these areas, pressure is applied to the wall of the tube at these points in such manner that all of the wires are sealed at the area B as shown in Fig. 4, and wires 'l and 9 only are sealed in at the area C, as shown in Fig. 6. The wire 8 is not sealed in the glassat the area C, but a space or clearance I is left between this wire and the glass, as shown in Fig. 6. Air under pressure is then introduced into the lower end of the tube, this air through the space l0 and forming an aperture Il in the upper portion of the wall of the tube, which is still hot from the application of heat `to the area B. The aperture I I provides means through which, in subsequent operations, the lamp is evacuated-and charged with an inert gas.

After the bulb l2 has been sealed to the flange of the tube and the lamp evacuated and filled with an inert gas, the wires are sealed within the tube at a point below the base of the lamp, as shown in Fig. '7, and the lower end of the tube is then melted olf or otherwise removed.

By the use of the foregoing method of manufacturing filament supporting assemblies, accurate placement` of the filaments is assured, greater uniformity in the assembly of the lamps is attained, and a considerable saving in the cost of manufacture of the lamp is effected.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims,

or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention:-

1. The method of manufacturing lament supporting assemblies for lamps which comprises flanging a tube intermediate its ends, inserting filament supporting Wires in said tube, sealing all of said wires insaid tube at one end of the tube and blowing an aperture in said tube adjacent said sealed end of the tube.

2. The method of manufacturing filament supporting assemblies for lamps which comprises vflanging a tube intermediate its ends, inserting filament supporting wires in said tube, sealing all of said wires in said tube at one end of the tube, sealing all but one` of the wires in the tube at a point adjacent said flange, and then admitting air into the tube through the space between the tube and the unseaied wire to form an aperture in said tube adjacent said sealed end of the tube.

3. The method of manufacturing filament supporting assemblies for lamps which comprises forming an outwardly extending flange on a glass tube intermediate its ends, inserting filament supporting wires in said tube, sealing all of said wires in said tube at one end of the tube, sealing all but one of the wires in the tube at a point at the opposite side of said flange from said sealed end of the tube, admitting air into the tube through the space between the tube and said unsealed Wire to form an aperture in said tube adjacent said sealed end of the tube, sealing a bulb to said flange, evacuating the bulb through said aperture, sealing the wires to the tube at the base of said bulb, and then removing a portion of said tube.

.4. The method of manufacturing filament supporting assemblies for lamps which comprises inserting filament supporting wires in spaced re- 1 lation in a tube and in such manner that the Wires project from one end of the tube, heating and compressing said end of the tube so as to seal all of the wires therein, and blowing air into the other end of the tube whereby to blow an aperture 4in said tube intermediate the ends of thevtube, said air being blown into said other end of the tube over an area confined only by the interior walls thereof.

5. The method of manufacturing filament supporting assemblies for lamps which comprises inserting lament supporting wires in spaced relation in an open-ended tube and in such manner that the wires project from one end of the tube, heating and compressing said end of the tube so as to seal all of the wires therein, heating and compressing a portion of the tube intermediate its ends so as to seal all but one of the Wires in the tube at such portion of the tube,-

wire to form an. aperture in said tube intermef diate the compressed portions of the tube.

6. The method of manufacturing filament supporting assemblies for lamps which comprises inserting filament supporting Wires in spaced relationsin an open ended glass tube, and in such manner that the wires project from one end of the tube, heating and compressing said end of the tube so as to seal al1 of the wires therein by means of the glass of the tube itself and without the use of glass' vrother than that of the tube, and blowing air into the opposite open end of the tube in order to form an air-exhausting aperture in the tube through the still-soft glass at the sealed end of the tube, the inner wall of the said tube forming a passageA for such air.

LEO S.v GREENMUN. 

